Highway crossing gate



Nov. 5, 1940. J c. LINDNER HIGHWAY CROSSING GATE Filed Dec. 24, 1938 m d a On .N m fl E n A J H Y B Patented Nov. 5, 1940 ZHGJGZ HIGHWAY CD08 SING GATE John O. Lindner, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application December- 24, 1938, Serial No. 247,587

llclalma.

This invention relates to crossing gates for blocking highway trafnc on a highway intersecting a railroad, and more particularly to a crossing gate operated wholly electrically. n In the electrical operation of crossing gates by reason of the length of such gates certain problems are encountered that have not been encountered in the electrical operation of semaphore blades for railway signalling purposes. One of the obstacles surrounding the economic operation of crossing gates is due to the enormous wind resistance offered by gates of a length to extend across a highway, by reason of which wind resistance the operation of the gate may be either aided or retarded depending on the direction of the wind. If the electrical operation of the gate is retarded this eilect may be compensated for by installing a higher gear ratio gear train or by employing a larger motor. If, on the 20 other hand, the direction of the wind is such as to aid the motor in moving the gate arm it is found necessary to add supplemental means for preventing excessive speed of operation of the gate arm. The second obstacle encountered when operating a crossing gate wholly electrically is the variable and greatly increased forces that are encountered when ice and sleet accumulates on the gate or the gate arm is broken ofl, as for instance by an automobile driving through the gate. This increased force when the gate is broken oil is due to the fact that the force exerted by the counterweight of the gate is in a direction to move the gate to its clear position and is considerably in excess of the biasing force that existed in the opposite direction before the gate was broken oil. In other words, the crossing gate by reason of its length is of considerable weight and ill in practice a counterweight of considerable:

weight is added so that the biasing force of the gate tending to move it to its stop position is almost entirely counter-balanced. If now the crossing gate is broken off, either due to excessive loading as by ice or sleet, or by being struck by an automobile, the counterweight alone remains, as a result of which the mechanism will be operated toward its clear position at a tremendous speed.

In accordance with the present invention it is proposed to employ a highway crossing gate which is provided with a counterweight to almost neutralize the torque produced by the gate and to provide a motor and suitable gearing for operating the gate to its clear vertical position, and to provide normally energized hold-clear mechanism for electrically holding the gate in its clear position, which hold-clear mechanism is released when the clearing potential is removed, to provide a friction slip clutch through the medium of which the hold-clear mechanism may retard the operation of the mechanism near the end of its clearing stroke and hold the gate against movement thereafter, and to provide electro-dynamic braking means to retard the operation of the crossing gate in its gravitational movement from the clear to the stop position, and to provide suitable pole changer contacts operated only when the gate arm is broken oil and when operated is effective to aflord a snubbing circuit to electro-dynamically brake the motor when the counterweight is moving from the stop to the clear position.

Other objects, purposes and characteristic features of the present invention will be pointed out in the following specification and will in part be obvious from the accompanying drawing showing a highway which crosses a railroad track and which highway is provided with electrically operated crossing gates embodying the present invention, the mechanical and electrical apparatus of only one of these crossing gates being shown.

Gate operating structure Referring to the drawing the railroad track illustrated is divided by insulating joints i into track circuits, each track circuit of which energizes one of the coils of the interlocking relay R. This interlocking relay R is preferably of the construction shown in either the patent to Field No. 1,824,131 or in the patent to Henry et al. No. 1,969,075. This interlocking relay R through front contacts 2 and 3 included in series controls the slow acting repeater relay RR. Each of the crossing gates 0 and P conventionally shown adjacent the highway comprises a gate plate P, having fastened thereto a gate arm Ill and a counterweight II. In practice this counterweight is so located and of such weight that the counterweight Ii will greatly aid in moving the gate ill to its clear position, but also of such weight that upon release of all extraneous forces the gate will gravitate to its horizontal stop position. To the gate is secured, as by bolts, 9. conducting link 8 of brittle metal, such as lead, zinc or cast iron, which link 8 is connected in series with the pole-changer relay PC and is also included in series with the energizing circuit for the reepater relay RR. Breaking of the gate arm will invariably break the link 8 and will result in deenergization of the relays PC and RR. This link 0 may, if desired, extend the entire length of the gate ID. This gate plate P is fastened to a main shaft l2, driven by the series motor M through the medium of gears l3, I4, l5, l8 and I1. This series motor M includes a series field winding F and an armature A. To the motor shaft 20 are keyed, but freely slidable, clutch plates 2|, of which only one has been illustrated, which clutch plates are pressed toward each other through the medium of a coil spring 22 and between these clutch plates 2| and freely rotatable on the shaft 20 is a clutch wheel 23. It is thus seen that this clutch wheel 23 is frictionally held from freely rotating on the shaft 20 by reason of the clutch plates 2! frictionally engaging opposite sides of this clutch wheel 23 due to the action of the coil spring 22.

Under normal operating conditions, that is, when the gate is in its clear position and the hold-clear mechanism HC is energized, the clutch wheel 23 which tends to rotate counterclockwise is locked in its then position by a locking pawl 25, This locking pawl 25 is slidably supported in one of the links of a toggle mechanism through the medium of three pins 26, 21 and 28 passing through the plates 28 and 30 of this link of the toggle mechanism, this locking pawl being biased into an engaging position by a spring 3|. These plates 29 and 38 are pivoted as by a pin 32 to a stationary lug 33. The lower end of these plates are pivoted, as by a pin 34 passing through the vertical arm 36 of the angle lever -36, this angle lever 35-36 being pivoted to stationary lugs through the medium of a pin 31.

This toggle mechanism is normally held in its efiective holding position by an electro-magnet including high resistance coils H and low resistance coils L. Upon deenergization of the magnet HC the weight of the armature 42 in addition to the force exerted on the pawl 25 will cause the pawl 25 to release. This electro-magnet includes the usual back yoke 48, cores 4| and armature 42. This electro-magnet when deenere gized causes the angle lever 35-36 to assume an abnormal position, where the stop pin 43 engages a stop plate 44, such that the locking pawl 25 no longer engages between the lugs on the clutch wheel 23. This electro-magnet is so constructed that if the high resistance coils H and the low resistance coils L are connected in series and energized by the source of direct current illustrated by the legends and there will be insufiicient flux to operate the hold-clear mechanism HC to its locking position. If, however, only the low resistance coils L are connected across this source of current the armature 42 will be operated to its attracted position, thereby operating the locking pawl 25 to a position to lock the clutch wheel 23. This electro-magnet will, however, maintain its armature 42 in its attracted condition, if once lifted to this position, by the flux emitted when the high resistance coils H and the low resistance coils L are connected in series across this source of current.

The shaft 45 illustrated by a dashed line is provided with three pairs of contacts 46-41, 48-49 and 50-5l. This shaft 45 is driven in accordance with the rotation of the shaft l2 through the medium of gear sectors 52 and 53. In order to provide electro-dynamic snubbing through the medium of the motor M when the crossing gate l8 gravitates to its horizontal stop position a snubbing relay SR has also been provided. This snubbing relay has a high resistance winding h and a low resistance winding 1.

For operation of the mechanism from the clear position to the stop position the residual magnetism in the field poles of the series motor M is of a magnetic polarity to induce a current in the armature which by flowing through the field winding will increase the magnetic strength of the field poles. This is particularly true because the armature A rotates in a reverse direction than when energized from the battery, so that the voltage generated in the armature is in a direction to create a series field current which flows in a direction to strengthen the residual magnetic field which produced such current. This flow of current will of course produce electro-dynamic braking of motor M. This current flows through the back contact 88 of the snubbing relay SR and through snubbing resistance 81. If now it is desired to produce electro-dynamic snubbing action when the gate arm l8 breaks, and the mechanism is operated from its stop to its clear position by gravity through the medium of the counterweight II, it is necessary to reverse either the field winding or the armature in the series motor M. In applicant's construction this desired result has been accomplished by including pole-changer contacts 56 and 51 in the series motor circuit which if operated to reverse position cause the armature to be reversed in this circuit, and these pole changer contacts are operated by the pole-changer relay PC, which relay PC is deenergized only when the link 8 is open circuited because the gate arm H! has been broken.

Operation of system Referring to the drawing, let us assume that there is a train approaching the highway and that as a result of this train one of the coils of the interlocking relay R is deenergized thereby opening the circuit for the repeater relay RR and resulting in the dropping of its contact 86. The opening of this contact 85 deenergizes the circuit including the high resistance coils H and the low resistance coils L of the hold-clear magnet in series. Deenergization of the magnet causes the armature 42 to drop thereby causing the locking pawl 25 to be moved to the left out of engagement with the slip clutch wheel 23. By reason of the weight of the crossing gate l0 over that of its counterweight II, this crossing gate will gravitate toward the horizontal position and in so doing will rotate the armature A of the motor M in the opposite direction from that in which the motor was last electrically operated. By reason of the residual magnetism remaining in the motor field a voltage will be built up in the armature A which will create a current in the snubbing circuit in a direction to flow in the field winding F in a direction to aid this residual magnetism, so that a comparatively strong magnetic field will be set up in the stator poles of the motor M, This strong magnetic field will of course set up a larger current through the snubbing circuit extending from the or ground connection, through the snubbing resistance 81, through the back contact 88 of the snubbing relay SR, through the field winding F of the motor M, through the pole-changer contact 56, through the armature A of the motor M, through pole changer contact 51, to the other ground or connection, thereby causing a reaction between the armature A and the field F of the motor M tending to retard the rotation of the armature A, and thereby retarding the speed of operation of the crossing gate l0 toward its horizontal stop position. If the prevailing wind should be in a direction to aid the return of the gate additional dynamic braking current will flow due to the slight increase in the motor speed thereby causing additional braking.

Let us now assume that the approaching train has passed the crossing and that the repeater relay RR is again energized. Energization of the repeater relay RR causes closing of its contact 86 thereby closing a circuit through the series motor M, which may be traced from the terminal of a suitable source of direct current, front contact 86 of the relay RR. contacts "-41 of the operating mechanism, low resistance winding 1 of the snubbing relay SR, the field 1' of the motor M, the pole-changer contact I, the armature A and the pole changer contact 51, to the other terminal of that source of current. The completion of this circuit will cause sufficient current to flow through the low resistance winding 1 of the snubbing relay SR to cause this snubbing relay SR to pick up and open its back contact 88. With the back contact I. of relay SR opened a useful multiple path for the motor M is established which includes the high resistance winding h of the relay SR, and the snubbing resistance 81. This multiple branch circuit including the high resistance winding h of the relay SR assures that the contact II will remain open in spite of sparking at the brushes and intermittent opening of the circuit of this motor M. As the motor M operates it turns the gear sector 53 in a clockwise direction and when it has operated through an angle of 85 degrees the contacts "-48 are closed and when it has reached the 87 degree position the contacts BO-Sl are closed. Closure of the contacts "-48 completes a circuit from the terminal through contacts IQ of relay RR, contacts "-41 and contacts 48-49 of the operating mechanism, through the low resistance winding L of the hold-clear magnet, as a result of which this hold-clear magnet is energized to an extent to pick up its armature 42. After three additional degrees of operation of the crossing gate ll,

" namely, when it has been operated to the 88 degree position from its horizontal position, the contacts 46-" of the operating mechanism open, thereby removing the shunt which had been established around the high resistance coils H of the hold-clear magnet by the contacts "-41, "-48 and 50- in series, as a result of which the high resistance coils H and the low resistance coils L of this hold-clear magnet are connected in series through a circuit including front contact 86 of the relay RR and contacts 50-5! of the operating mechanism in series. This circuit by reason of the high resistance of the coils H draws very little current but at the same time is able to maintain the armature 42 in its raised position. When the armature 42 of the hold-clear mechanism was actuated to its attracted position the locking pawl 25 of course erfiaged the friction wheel 23 of the friction slip clutch as a result of which a braking action is applied to the motor M. The slipping between the friction wheel 23 and the clutch plates II will soon bring the motor M to a stop.

In order to prevent the crossing gate from being operated and held beyond the 91 degree position the contacts 50-5l have been made so short as to be closed only between the 87 degree and the 91 degree position. It thus follows that if the gate is operated beyond the 91 degree position the hold-clear magnet will be dcenergized by the opening of the contacts ll-ll. If the gate now settles back below the 91 degree position and the contacts ill-5i reclose the circuit for the hold-clear magnet its armature 42 will not be picked up, because it is incapable of being picked up by a circuit including the high resistance coils H and the low resistance coils L in series. Thegate willthus be returned a little further and when it reaches the 88 degree position and the contacts 46-" of the operating mechanism reclose, the circuits renergizing the motor M and for shunting the high resistance coils H of the hold-clear magnet are cloud so that this hold-clear magnet will be picked up through its low resistance coils L.

Let us now assume that the crossing gate is assuming its stop position and that an automobile strikes the gate and breaks oi! the arm II at Just about the time that the train passes beyond the crossing and picks up the repeater relay RR. When this occurs the circuit for the motor M heretofore traced is not completed because breaking of the gate arm III and its check or conducting link 8 causes dropping of the relay RR, so that the motor circuit is not completed. This breaking of the check link 8 also causes dropping of the pole-changer relay PC. With the relay PC denergized a snubbing or dynamic braking circuit is closed which includes the armature connections reversed, that is, a snubbing circuit that will function for operation of the motor in the gate clearing direction. In other words, if the crossing gate was assuming the stop position when the gate arm was broken off, as has been assumed, then the gravitational force of the counterweight I l, which is no longer counter-balanced by the gate, will act tending to assume the clear position very quickly, which would have broken the mechanism upon reaching the end of the stroke were it not for the special snubbing circuit that was completed by dropping of the pole-changer relay PC. This special snubbing circuit includes the armature and the field of the motor M so connected in series that the voltage generated in the armature A when rotating in the clearing direction produces a current in the field winding to increase the field strength and the voltage generated so that each increases the other to cause a large dynamic braking current to flow in the snubbing circuit including the snubbing resistance 81.

The applicant has thus shown and described an electrically operated crossing gate embodying certain new features including novel electrodynamic braking means for retarding the speed of the operating mechanism for any reason as, for instance, due to the breaking of the crossing gate, which would result in a tremendous torque being exerted upon the mechanism due to the force of the counterweight which normally counter-balances the gate itself. Although a rather specific construction of applicant's invention has been illustrated in the drawing it is desired to be understood that this has been done to facilitate description of the invention rather than to illustrate its scope or the particular construction preferably employed in practicing the invention, and it is further desired to be understood that such changes as are within the scope of the appending claims may be made without departing from the spirit or scope of the present invention.

What I claim as new is:

1. In an electrically operated crossing gate, the combination with a crossing gate pivoted to a stationary support and partially counterbalanced so as to be biased toward the horizontal stop position only to an extent to move to and return its operating mechanism to such stop position, an electric motor and reduction gearing for operating said gate to. a substantially vertical clear position, a shaft for said motor, a friction slip clutch on said shaft, a hold-clear mechanism effective to engage said clutch to render it effective when said motor is energized and said gate is in its clear position, a check link on said gate electrically broken when said gate is broken off, and a snubbing circuit effective to brake said motor when running in a clearing direction effective only if said check link is broken.

2. In an electrically operated crossing gate, the combination with a crossing gate pivoted to a stationary support and partially counterbalanced so as to be biased toward the horizontal stop position only to an extent to move to and return its operating mechanism to such stop position, a series motor and reduction gearing for operating said gate to a substantially vertical clear position, a shaft for said motor, a friction slip clutch on said shaft, a hold-clear mechanism effective to engage said clutch to render it effective when said motor is energized and said gate is in its clear position, a snubbing circuit closed when saidmotor is disconnected from the source of current and effective to electro-dynamically brake said motor when it is turned in a direction opposite to the direction in which it is operated to move said gate to its clear position, a check link on said gate electrically broken when said gate is broken off, and means for reversing the armature with respect to its field of said motor in said snubbing circuit when said check link is broken, whereby said motor is dynamically braked for operation of said operating mechanism toward its clear position.

3. In an electric motor operated crossing gate, the combination with a gate fastened to a horizontal shaft and partly counterbalanced by a counterweight so that the shaft is biased to a horizontal stop position but is very strongly biased to a clear position if the gate is broken off, a gear train, a series motor for operating said shaft to a clear position through the medium of said gear train, a snubbing circuit including in series said motor and a snubbing resistance for electro-dynamically braking said motor when operated in a direction to rotate said shaft from a clear position to a stop position, and means for reversing the armature with respect to the field of said series motor when said gate is broken off, whereby said snubbing circuit functions for operation of said motor from the stop position to the clear position.

4. In an electric motor operated crossing gate, the combination with a gate fastened to a horizontal shaft and partly counterbalanced by a counterweight so that the shaft is biased to a horizontal stop position but is very strongly biased to a clear position if the gate is broken off, a gear train, a series motor for operating said shaft to a clear position through the medium of said gear train, a clutch wheel frictionally connected to the shaft of said series motor; a holdclear magnet having a high resistance coil and a low resistance coil and which if in an active condition locks said clutch wheel; a control relay; a first contact, a second contact and a third contact controlled by said shaft of which the first contact opens when said shaft assumes a predetermined position and of which the second contact and third contact close when said shaft has almost reached said predetermined position; an operating circuit for said motor including a contact of said control relay, a source of current and said first contact; a circuit for said low resistance coil including in series said source, a contact of said control 'relay said first contact and said second contact in series; a circuit for said high resistance coil and said low resistance coil in series including a contact of said control relay, said source and said third contact; a snubbing circuit for said motor including in series said motor and a snubbing resistance; and means for reversing the armature with respect to the field of said series motor and for deenergizing said control relay when the gate is broken off.

5. In an electric motor operated crossing gate, the combination with a gate fastened to a horizontal shaft and partly counterbalanced by a counterweight so that the shaft is biased to a horizontal stop position but is very strongly biased to a clear position if the gate is broken ofi, a gear train, a series motor for operatingsaid shaft to a clear position through the medium of said gear train, a clutch wheel frictionally connected to the shaft of said series motor; a holdclear magnet having a high resistance coil and a low resistance coil and which if in an active condition locks said clutch wheel; a control relay; a snubbing relay, a first contact, a second contact and a third contact controlled by said shaft of which the first contact opens when said shaft assumes a predetermined position and of which the second contact and third contact close when said shaft has almost reached said predetermined position; a pole-changer relay; an operating circuit for said motor including a contact of said control relay, a source of current, contacts of said pole-changer relay, a winding of said snubbing relay and said first contact; a circuit for said low resistance coil including inseries said source, a contact of said control relay, said first contact and said second contact in series; a circuit for said high resistance coil and said low resistance coil in series including a contact of said control relay, said source and said third contact; a first snubbing circuit for said motor including in series said motor, contacts of said pole-changer relay closed when said pole-changer relay is energized, a back contact of said snubbing relay and a snubbing resistance; and a second snubbing circuit including the same elements as said first snubbing circuit but with the contacts of said pole-changer relay reversed so that the armature of said series motor is reversed with respect to the field winding of such series motor.

6. In an electric motor operated crossing gate, the combination with a gate fastened to a horizontal shaft and partly counterbalanced by a counterweight so that the shaft is biased to a horizontal stop position but is very strongly biased to a clear position if the gate is broken off, a gear train, a series motor for operating said shaft to a clear position through the medium of said gear train, a clutch wheel frictionally connected to the shaft of said series motor; a holdclear magnet having a high resistance coil and a low resistance coil and which if in an active condition locks said clutch wheel; a control relay; a snubbing relay, a first contact, a second contact and a third contact controlled by said shaft of which the first contact opens when said shaft assumes a predetermined position and of which the second contact and third contact close when said shaft has almost reached said predetermined position; a pole-changer relay; an operating circuit for said motor including a contact of said control relay, a source of current, contacts of said pole-changer relay, a winding of said snubbing relay and said first contact; a circuit for said low resistance coil including in series said source, a contact of said control relay, said first contact and said second contact in series; a circuit for said high resistance coil and said low resistance coil in series including a contact of said control relay, said source and said third contact; a first snubbing circuit for said motor including in series said motor, contacts of said pole-changer relay closed when said pole-changer relay is energized, a back contact of said snubbing relay and a snubbing resistance; a second snubbing circuit including the same elements as said first snubbing circuit but with the contacts of said pole-changer relay reversed so that the armature of said series motor is reversed with respect to the field winding of such series motor; and means for deenergizing said control relay and said polechanger relay simultaneously.

7. In an electrically operated crossing gate, the combination with a gate arm pivotally supported through the medium of a horizontal shaft to which this gate arm is secured, a gear train, a series motor for operating said gate arm through the medium 01' said gear train, a counterweight for almost entirely counterbalancing said gate arm allowing however suflicient bias so that said gate arm by gravitational forces acting thereon may operate said motor and gear train to the stop position from the clear position, a control relay, a pole changer relay, a control circuit for operating said gate arm to the clear position including a source of current and contacts of said control relay and said pole changer relay closed when said relays are in their energized condition, a first snubbling circuit ineluding contacts or said pole changer relay closed when such pole changer relay is in its energizing condition and a snubbing resistance, and a second snubbing circuit including contacts oi. said pole changer relay closed only when said pole changer relay is deenergized and including said snubbing resistance.

8. In an electrically operated crossing gate, the combination with a gate arm pivotally supported through the medium of a horizontal shaft 80 to which this gate arm is secured, a gear train, a series motor for operating said gate am through the medium of said gear train, a counterweight for almost entirely counterbalancing said gate arm allowing however sumcient bias 8 so that said gate arm by gravitational forces acting thereon may operate said motor and gear train to stop position from the clear position, a

control relay, a pole changer relay, 9. control circuit for operating said gate arm to the clear position including a source of current and contacts of said control relay and said pole changer relay closed when said relays are in their energized condition, a first snubbing circuit including contacts of said pole changer relay closed when such pole changer relay is in its energizing condition and a snubbing resistance, a second snubbing circuit including contacts of said snubbing circuit closed only when said pole changer relay is deenergized and including said snubbing resistance, and means for deenergizing said pole changer relay when said gate arm is broken oil.

9. In a power operated crossing gate, in combination, power operated means, a movable gate positionable horizontally or vertically, means only partly counterbalancing the gate so the gate is biased to the horizontal position only to an extent to move to, and return its operating mechanism to, the horizontal position, a check link on the gate and made efiective only when the gate is broken, and brake means controlled by the check link, and efiective, only when the check link is eflective, to brake the power operated means when it is moving in a direction to move the gate to its vertical position.

10. In a power operated crossing gate, in combination, electric power operated means, a pivoted-gate positionable horizontally or vertically, means only partly counterbalancing the gate so the gate is biased to the horizontal position only to an extent to move to, and return its operating mechanism to, the horizontal position, a check link on the gate and made eflective only when the gate is broken, and dynamic brake means controlled by the check link and eflective, only when the check link is effective, to brake the power operated means when it is moving in a direction to move the gate to its vertical position.

11. In a power operated crossing gate, in combination, electric power operated means, a pivoted gate positionable horizontally or vertically, means only partly counterbalancing the gate so the gate is biased to the horizontal position only to an extent to move to, and return its operating mechanism to, the horizontal position, a check link on the gate and made eflective only when the gate is broken, and dynamic brake means controlled by the check link and effective, only when the check link is eflective, to brake the power operated means only when it is moving in a direction to move the gate to its vertical position.

JOHN C. LINDNER. 

